Molar pregnancy Flashcards
What is gestational trophoblastic disease (GTD)?
used to describe group of pregnancy-related tumours; split into pre-malignant and malignant conditions
What are the 2 groups of types of gestational trophoblastic disease?
- Pre-malignant conditions e.g. partial molar pregnancy and complete molar pregnancy
- Malignant conditions e.g. invasive mole, choriocarcinoma, placental trophoblastic site tumour and epithelioid trophoblastic tumour
Of the 2 types of gestational trophoblastic disease, which type is more common?
Pre-malignant conditions more common than malignant conditions
What are 2 types of pre-malignant GTD?
- Partial molar pregnancy
- Complete molar pregnancy
What are 4 malignant forms of GTD?
- Invasive mole
- Choriocarcinoma
- Placental trophoblastic site tumour
- Epithelioid trophoblastic tumour
What, broadly speaking, is the cause of molar pregnancies?
abnormality in chromosomal number during fertilisation
What is the cause of partial molar pregnancy?
one ovum with 23 chromosomes is fertilised by two sperm, each with 23 chromosomes - results in triploidy (cells with 69 chromosomes)
If a partial mole exists with a viable fetus, what is going on genetically in the cells of the fetus and placenta?
the fetus and placenta are usually triploid, however mosaicism can exist where the fetus has a normal karyotype and triploidy is confined to the placenta
What is the cause of complete molar pregnancy?
one ovum without any chromosomes is fertilised by one sperm which duplicates, or (less commonly) two different sperm, leading to 46 chromosomes of paternal origin alone
How do invasive moles differ from benign molar tumours?
they invade into the uterine myometrium and disseminate around the body. benign molar pregnancy can become malignant
What is choriocarcinoma?
malignancy of the trophoblastic cells of the placenta, commonly co-exists with a molar pregnancy
Where does a choriocarcinoma characteristically metastasise to?
lungs
What is a placental site trophoblastic tumours?
malignancy of the intermediate trophoblasts which are normally responsible for anchoring the placenta to the uterus
What are 3 things that a placental site trophoblastic tumours can arise from and which is most common?
- Normal pregnancy → most common
- Molar pregnancy
- Miscarriage
What is an epithelioid trophoblastic tumour?
malignancy of the trophoblastic placental cells, which can be very difficult to distinguish from choriocarcinoma
What type of cancer does an epithelioid trophoblastic tumour mimic the cytological features of?
squamous cell carcinoma